This invention discloses a drying mechanism used in a printing plate coating process. The drying mechanism comprises a hood body; a plurality of rollers are rotationally arranged on the inner wall of the opening end of the hood body; two main gas pipes are arranged on the outer walls of the two sides of the hood body; the tail end of an upper supporting rod and the tail end of a lower supporting rod are each provided with a rubber wheel; the lower segment of each main gas pipe is provided with a branch gas pipe; the tail of an extending segment of each main gas pipe is connected with an upper spraying head; the tail of an extending segment of each branch gas pipe is connected with a lower spraying head; straight-through flow in upper spraying holes corresponds to the side wall of the upper end portion of an aluminum substrate; and straight-through flow in lower spraying holes corresponds to the side wall of the middle portion of the aluminum substrate. The inventor changes an existing drying manner; the drying procedure of a coating layer of the aluminum substrate is performed in the hood body; the gas spraying holes in the upper spraying heads and the lower spraying heads are used for jetting gas flow to continuously wash the two sides of the aluminum substrate, so that the defect that in the prior art, hot gas flow of a water tank structure must be replaced after several times of drying is avoided, the gas consumption amount of the hot gas flow is greatly reduced, and meanwhile, the drying effect of the aluminum substrate is improved.